26 January 1944:
Off Labuan. The convoy joins convoy 3203 that sailed from Miri, Borneo that same day. The combined convoy consists of NITTATSU MARU, tankers RONSAN, SAN PEDRO and TAKETOYO MARUs and four unidentified merchant ships escorted by WAKATAKE and torpedo boat MANAZURU.

12 February 1944:
East China Sea. LtCdr Russell Kefauverís USS TAMBOR (SS-198), sights smoke at 25,000 yards. By 1730, Kefauver is able to make out the convoy consisting of four ships and three escorts.

At 1921, unable to maneuver for a submerged attack, Kefauver surfaces TAMBOR and closes the targets on her four diesel engines. At 2052, he fires three torpedoes by SJ radar and submerges to avoid the escorts.

Between 2052 and 2054, TAMBORís crew hears one hit that sinks RONSAN MARU off Okinoerabu Island, about 40 miles SW of Amami O-Shima, Ryukyus at 27-44N, 128-42E. 17 crewmen and 2 gunners are KIA.